JP2018091199A - Impeller, water heater, resin molding die, and method of manufacturing impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impeller integrally formed with resin and achieving a stable air-blowing performance.SOLUTION: An impeller integrally formed with resin includes an annular shroud, a main plate having a boss part in a central section, and a plurality of blades. Each of the blades is arranged between the shroud and the main plate so as to connect the shroud and the main plate. The shroud has a plurality of first gate mark portions, and the main plate has a plurality of second gate mark portions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an impeller, a hot water heater, a resin molding die, and an impeller manufacturing method.

  The impeller is a rotating body that rotates about a rotation axis. When the shape of the rotating body is distorted, vibration and noise are generated, or the air blowing performance is reduced. The impeller itself may be damaged due to the occurrence of vibration. Thus, since distortion of the shape of an impeller makes it difficult to exhibit stable blowing performance, the shape needs to be sufficiently reduced in distortion.

  For example, Japanese Patent Laying-Open No. 2006-044622 (Patent Document 1) discloses a resin impeller that includes a first member having a shroud and first blades and a second member having a main plate and second blades. It is disclosed. In Patent Document 1, after the first member and the second member are integrally formed by a resin molding method using a resin molding die, both members are welded by an ultrasonic welding method. Impellers that exhibit stable blowing performance are manufactured.

JP, 2006-044622, A

  By the way, from the viewpoint of manufacturing cost, a technique for integrally forming an impeller only by a resin molding method is required.

  The present invention has been made in view of the above-described problems, and an object of the present invention is an impeller integrally formed of resin, an impeller that exhibits stable blowing performance, a water heater, and a resin molding It is providing the manufacturing method of a metal mold | die and an impeller.

  An impeller according to the present invention is an impeller integrally formed of resin, and includes an annular shroud, a main plate having a boss portion at a central portion, and a plurality of blades. Each of the blades is disposed between the shroud and the main plate so as to connect the shroud and the main plate. The shroud has a plurality of first gate trace portions, and the main plate has a plurality of second gate trace portions.

  The impeller of the present invention can be integrally formed using a resin molding die having a cavity corresponding to the shape of the impeller. In particular, in the impeller, since a plurality of first gate traces are present on the shroud and a plurality of second gate traces are present on the main plate, the resin molding die for manufacturing the impeller is a shroud. It is understood that a gate that leads to a cavity corresponding to the shape of the main plate (hereinafter also referred to as a “cavity for shroud”) and a gate that leads to a cavity corresponding to the shape of the main plate (hereinafter also referred to as “cavity for the main plate”) are understood. The

  If an impeller is manufactured using a resin molding die having only a gate that leads to a shroud cavity, the resin injected from the gate into the cavity is a cavity corresponding to the shape of the blade from the shroud cavity (hereinafter, The main plate cavity is filled through the “blade cavity”. In this case, the amount of resin that reaches the main plate cavity tends to be insufficient, and accordingly, the resin density in the main plate cavity becomes non-uniform. Since the main plate having a non-uniform resin density shrinks non-uniformly during curing, the main plate includes distortion after curing.

  On the other hand, as described above, the impeller of the present invention is manufactured using a resin molding die having a gate that leads to the shroud cavity and a gate that leads to the main plate cavity. Therefore, in the impeller of the present invention, the non-uniformity of the resin density in the main plate is reduced, whereby the distortion of the shape is reduced or eliminated, and a stable blowing performance can be exhibited.

  In the impeller, the shroud has a first surface and a second surface opposite to the first surface, and the main plate has a third surface facing the second surface, and the opposite side to the third surface. And a fourth surface. The first gate trace portion and the second gate trace portion are located on the first surface and the third surface, respectively. In this case, in the resin molding die, the arrangement position of the first gate that communicates with the shroud cavity and the arrangement position of the second gate that communicates with the main plate cavity can be brought close to each other. For this reason, the structure of the resin molding die can be simplified, and the manufacturing cost of the impeller can be reduced.

  In the impeller, the shroud has an opening, and the main plate is included in the opening in a plan view as viewed from the axial direction of the impeller. Thereby, the shape of the resin molding die can be simplified, and the manufacturing cost of the impeller can be reduced. Further, the manufacturing yield can be improved.

  The said impeller is located in the axial center side rather than a 1st gate trace part in the planar view seen from the axial direction of the impeller. As a result, the shape of the resin molding die can be simplified, the manufacturing cost of the impeller can be reduced, and the manufacturing yield can be improved.

  In the impeller, the weld line is located on the main plate. In this case, the occurrence of breakage due to the presence of the weld line can be reduced.

  In the impeller, the first gate trace is located immediately above the connection between the blade and the shroud. Thereby, since the resin can be sufficiently and uniformly filled in the blade cavity at the time of manufacturing, the uniformity of the shape of each blade can be improved.

  In the above impeller, the dimension of the first gate trace is larger than the dimension of the second gate trace. The flow rate of the resin flowing into the cavity from the gate tends to be proportional to the size of the gate trace. That is, in this impeller, resin (hereinafter also referred to as “first resin”) is injected from the first gate at a relatively high flow rate, and resin (hereinafter referred to as “second resin”) at a relatively low flow rate from the second gate. Is manufactured by being injected. In this case, it becomes easy to prepare so that the joining position of the first resin and the second resin is not the blade cavity but the main plate cavity. In other words, according to this impeller, since the weld line can be positioned on the main plate, occurrence of breakage due to the weld line can be suppressed.

  In the impeller, the number of first gate trace portions is larger than the number of second gate trace portions. Thereby, the flow rate of the resin flowing from the first gate into the shroud cavity can be made larger than the flow rate of the resin flowing from the second gate into the main plate cavity. In this case, it becomes easy to prepare so that the joining position of the first resin and the second resin is not the blade cavity but the main plate cavity. In other words, according to this impeller, since the weld line can be positioned on the main plate, occurrence of breakage due to the weld line can be suppressed.

  Moreover, the water heater of this invention is equipped with said impeller. Since said impeller can exhibit the stable ventilation performance, according to the water heater provided with this, stable hot water supply is attained.

  The resin molding die of the present invention is a resin molding die for manufacturing the impeller, and includes a cavity corresponding to the impeller and a first of the cavities corresponding to the shroud. A gate, and a second gate provided at a position corresponding to the main plate in the cavity. According to this resin molding die, the impeller can be manufactured.

  The impeller manufacturing method of the present invention includes a step of preparing the resin molding die and a step of injecting resin into the cavity through the first gate and the second gate. According to this impeller manufacturing method, the impeller can be manufactured.

  As described above, according to the present invention, an impeller integrally formed of resin, which is an impeller, a water heater, a resin molding die, and an impeller that exhibits stable blowing performance. A manufacturing method can be provided.

It is a perspective view showing roughly the composition of the impeller in one embodiment of the present invention. It is a front view which shows schematically the structure of the impeller in FIG. It is a rear view which shows schematically the structure of the impeller in FIG. It is sectional drawing which shows schematically the structure of the impeller in FIG. It is sectional drawing which shows schematically the structure of the metal mold | die for resin molding in one Embodiment of this invention. It is a figure which shows roughly the structure of the water heater using the impeller shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships. Moreover, in each figure, the same code | symbol is attached | subjected about the same element and the description is not repeated.

<Composition of impeller>
The impeller of this embodiment is demonstrated referring FIGS. 1-4. The impeller 10 shown in FIGS. 1 to 4 is an integrally molded product integrally formed of resin, and mainly includes an annular shroud 1, a main plate 2, and a plurality of blades 4.

  The shroud 1 has a first surface 1A and a second surface 1B opposite to the first surface 1A, and has an opening 1C at the center thereof. Generally, the shape of the “shroud” of the impeller is formed along the height of the covering blade so as not to hinder the flow of gas passing between the blades. The shroud 1 of the present embodiment has an annular shape in a plan view when viewed from the axial direction of the impeller 10, and has a truncated cone shape with a narrowed stop in a cross section parallel to the axial direction.

  The axial direction of the impeller 10 means a direction along the central axis in the rotational operation of the impeller 10. 1 to 4, the central axis is indicated by a one-dot chain line X. Further, the shape of the shroud 1 may be an annular shape that can operate as the impeller 10, and is not limited to an annular shape. However, from the viewpoint of blowing performance, an annular shape is preferable.

  The shroud 1 further includes a plurality of first gate trace portions 1D. In this embodiment, the 1st gate trace part 1D is located in the 1st surface 1A of the shroud 1, and is located in the circumference at equal intervals. Further, as shown in FIG. 2, each first gate trace portion 1 </ b> D is located immediately above the connection portion between each blade 4 and the shroud 1.

  The main plate 2 has a third surface 2A that opposes the second surface 1B of the shroud 1 and a fourth surface 2B that opposes the third surface 2A, and has a boss 3 at the center thereof. A bearing hole 3a that penetrates from the third surface 2A side to the fourth surface 2B side is provided at the center of the boss portion 3.

  In the present embodiment, the main plate 2 has a disk shape in which a bearing hole 3a is provided in the center portion in a plan view viewed from the axial direction, and a cone having a narrowed stop in a cross section parallel to the axial direction. It has a trapezoidal shape.

  The main plate 2 further has a plurality of second gate trace portions 2D. In the present embodiment, the second gate traces 2D are located on the third surface 2A of the main plate 2 and are equally spaced on the circumference. As shown in FIGS. 1 and 2, each second gate trace portion 2 </ b> D is located on the inner peripheral side of the main plate 2, which is a region where the blades 4 do not extend.

  Further, the main plate 2 is positioned so as to be included in the opening 1 </ b> C of the shroud 1 in a plan view seen from the axial direction. That is, the outer shape of the main plate 2 is smaller than the outer shape of the opening 1C.

  The blades 4 are arranged between the shroud 1 and the main plate 2 so as to connect the shroud 1 and the main plate 2. Specifically, the blade 4 extends from the outer peripheral side of the second surface 1B of the shroud 1 to the inner peripheral side, and further extends to the outer peripheral side of the first surface 1A of the main plate 2, thereby forming the main plate 2. Has reached. The blades 4 exist individually and do not touch each other.

  The height of the blade 4 in the protruding direction (the vertical width in FIG. 4) increases continuously (relatively gently) from the outer peripheral side of the shroud 1 toward the inner peripheral side, and the inner peripheral side of the shroud 1. Until it reaches the outer peripheral side of the main plate 2 and becomes smaller (relatively abruptly).

  The impeller 10 provided with the blades 4 having such a structure is one that earns blowing power by the length in the extending direction of the blades 4, and is different from a sirocco fan that earns blowing force by the height of the blades in the protruding direction. It is.

  The impeller 10 of the present embodiment further includes an outer edge ring 5. The outer ring 5 has an annular shape in a plan view viewed from the axial direction of the impeller 10 and is positioned so as to include the shroud 1. An end of each blade 4 is connected to the outer ring 5.

<Water heater with impeller>
An example of the water heater provided with the impeller 10 of the present embodiment will be described with reference to FIG. In the water heater 100 of FIG. 5, the impeller 10 is disposed in the fan case of the fan 20.

  Referring to FIG. 5, water heater 100 mainly has a hot water supply path, a bath circulation path, a hot water supply path, and a drain discharge path. That is, the water heater 100 is a bath water heater.

  The hot water supply path of the water heater 100 is a path for heating clean water. This hot water supply path is composed of a primary heat exchanger 40A, a secondary heat exchanger 50A, a combustion device 60A, pipes 71 to 73, a distribution valve 74, and the like.

  One end of the pipe 71 has a water inlet. The water inlet is connected to the water supply. The other end of the pipe 71 is connected to one end of the secondary heat exchanger 50A. The other end of the secondary heat exchanger 50A is connected to one end of the primary heat exchanger 40A. The other end of the primary heat exchanger 40 </ b> A is connected to one end of the pipe 72. The other end of the pipe 72 is connected to a curran outside the water heater 100. The distribution valve 74 is connected to the pipe 71. The distribution valve 74 and the pipe 72 are connected by a pipe 73.

  A combustion device 60A is disposed in the vicinity of the heat exchanger 40A. The combustion device 60 </ b> A has a plurality of combustion pipes 61.

  The bath circulation path of the water heater 100 is a path for heating the hot water in the bathtub 90. This bath circulation path includes the fan 20, the primary heat exchanger 40B, the secondary heat exchanger 50B, the combustion device 60B, the pipes 82 and 83, the circulation pump 84, and the like.

  One end of the pipe 82 is connected to one end of the secondary heat exchanger 50B. The other end of the secondary heat exchanger 50B is connected to one end of the primary heat exchanger 40B. The other end of the primary heat exchanger 40 </ b> B is connected to one end of the pipe 83. Each of the other end of the pipe 82 and the other end of the pipe 83 is connected to a circulation adapter 91 disposed in the bathtub 90. The piping 82 is provided with a circulation pump 84.

  A combustion device 60B is disposed in the vicinity of the heat exchanger 40B. The combustion device 60 </ b> B has a plurality of combustion tubes 61.

  The hot water supply path of the water heater 100 is a path through which hot water flows from the hot water supply path to the bath circulation path. This pouring route is constituted by a pouring solenoid valve 76, check valves 77 and 78, an air release valve 79, pipes 75, 80, 81, and the like.

  A pipe 81 branched from the pipe 72 of the hot water supply path is connected to a circulation pump 84 of the bath circulation path. In the pipe 81, a pouring electromagnetic valve 76, a check valve 77, and a check valve 78 are arranged in this order. An air release valve 79 is connected to the path of the pipe 81 between the check valve 77 and the check valve 78.

  The air release valve 79 can be opened and closed in response to the fluid pressure in the pipe 71 given through the pipe 75. When the atmosphere release valve 79 is opened, the atmosphere release valve 79 can discharge fluid from the path of the pipe 81 between the check valve 77 and the check valve 78 to the outside of the water heater 100 through the pipe 80. .

  The drain discharge path of the water heater 100 is a path for discharging the drain generated in the secondary heat exchangers 50 </ b> A and 50 </ b> B to the outside of the water heater 100. The drain discharge path includes a drain tank 86, pipes 85 and 87, and the like. Drain generated in the secondary heat exchangers 50 </ b> A and 50 </ b> B can be stored in the drain tank 86 through the pipe 85. The drain in the drain tank 86 can be discharged to the outside of the water heater 100 through the pipe 87.

  The combustion device 60A has a plurality of combustion regions BR1, BR2, and BR3. These combustion regions BR1, BR2, and BR3 can perform combustion operations at different timings or at the same time.

  Specifically, the combustion region BR2 can perform a combustion operation at a timing different from that of the combustion region BR1. The combustion region BR3 can perform a combustion operation at a timing different from each of the combustion regions BR1 and BR2.

  The combustion device 60B is composed of, for example, a single combustion region BR4. However, the combustion device 60B may be composed of a plurality of combustion regions, like the combustion device 60A.

  A gas pipe 65 is connected to each of the combustion devices 60A and 60B. The gas pipe 65 is for supplying fuel gas to each of the combustion devices 60A and 60B. An original gas electromagnetic valve 64 and a gas proportional valve 63 are connected to the gas pipe 65.

  Further, the gas pipe 65 is branched into, for example, four paths. Each of the four-path branched gas pipes 65 is connected to each of the combustion regions BR1, BR2, BR3, BR4. Each of the branched gas pipes 65 is connected to each of the electromagnetic valves 62a to 62d. The supply of fuel gas to each of the branched gas pipes 65 can be controlled by the opening / closing operations of the electromagnetic valves 62a to 62d. Thus, by independently controlling the open / close states of the electromagnetic valves 62a to 62d, it is possible to independently adjust the combustion states of the combustion regions BR1 to BR4.

<Mold for resin molding to manufacture impeller>
With reference to FIG. 6, a resin molding die used in the manufacturing method of the impeller of this embodiment will be described.

  A resin molding die 200 shown in FIG. 6 includes a first die 210 and a second die 220. A cavity 230 corresponding to the shape of the impeller 10 is formed in the resin molding die 200. In the resin molding die 200, a position corresponding to the shroud in the cavity 230, that is, a first gate 240a provided so as to communicate with the shroud cavity, and a position corresponding to the main plate, that is, the main plate. And a second gate 240b provided to communicate with the cavity.

  The first gate 240a is disposed in a portion of the shroud cavity that is located directly above the connection portion with the blade cavity. Further, each of the first gates 240a is arranged on the circumference on the annular shroud cavity, and each of the second gates 240b is arranged on the circumference on the disk-shaped main plate cavity.

As shown in FIG. 6, each of the first gate 240a and the second gate 240b is a pin gate. In the present embodiment, the radial dimension W _{1 of} the first gate 240a is designed to be larger than the radial dimension W _{2 of} the second gate 240b.

  In FIG. 6, the first mold 210 and the second mold 220 are illustrated as one piece, but each mold may be composed of a plurality of members in consideration of, for example, the arrangement of ejector pins. FIG. 6 shows a state in which the resin injected from the first gate 240 a and the second gate 240 b fills the cavity 230.

<Manufacturing method of impeller>
The manufacturing method which manufactures the impeller of this embodiment using the above-mentioned resin mold is demonstrated.

  First, the above resin molding die is prepared. Next, resin is injected into the cavity 230 from the first gate 240a and the second gate 240b.

  As a result, the first resin that has flowed into the shroud cavity via the first gate 240a is filled into the shroud cavity. Of the first resin, the first resin that has passed through the shroud cavity flows into the blade cavity and fills the blade cavity. Of the first resin, the first resin that has passed through the blade cavity continues to flow into the main plate cavity. On the other hand, the second resin that has flowed into the main plate cavity via the second gate 240b is filled into the main plate cavity.

  Here, the inflow amount and / or the inflow speed of each resin may be controlled so that the second resin does not flow into the blade cavity, that is, the first resin fills the shroud cavity and the blade cavity. preferable. This is because the weld line occurrence position in the impeller 10 is not the blade 4 but the main plate 2.

For example, if the dimension W ₁ of any one first gate 240a is larger than the dimension W _{2 of} any one second gate 240b, the flow rate of the first resin flowing from the one first gate 240a (ml / Min) is larger than the flow rate (ml / min) of the second resin flowing from the second gate 240b. When the number of the first gates 240a is larger than the number of the second gates 240b, the total flow rate of the first resin flowing from all the first gates 240a is the total amount of the second resin flowing from all the second gates 240b. It becomes larger than the flow rate. In addition, it is necessary to adjust the inflow amount of each resin in consideration of the ratio between the volume of the shroud cavity and the volume of the blade cavity and the volume of the main plate cavity.

  Examples of the resin used include fluorine such as polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), syndiotactic polystyrene (SPS), polyvinyl chloride (PVC), phenol resin, epoxy resin, silicone resin, and polytetrafluoroethylene. Resin, unsaturated polyester resin, melamine resin, polycarbonate resin, methacryl styrene (MS) resin, methacryl resin, AS resin (styrene acrylonitrile copolymer), ABS resin (acrylonitrile, butadiene, styrene copolymer synthetic resin), polyethylene, polypropylene, polystyrene And polyethylene terephthalate (PET). Moreover, you may use resin containing a fibrous filler. An example of the filler is glass fiber.

  After all of the inside of the cavity 230 is filled with the resin, the resin molded body is taken out from the mold for resin molding after the resin is cured. Of the resin molded body that has been taken out, a portion that is filled and cured in the first gate 240a and the second gate 240b is removed. The impeller 10 which is a resin molding is manufactured by the above.

  As described above, the impeller 10, the water heater 100 including the impeller 10, the resin molding die 200 for manufacturing the impeller 10, and the manufacturing method of the impeller 10 have been described in detail.

  As described above, the impeller 10 is a resin molded body manufactured by the above-described manufacturing method using the resin molding die 200. According to the above-described manufacturing method, usually, a part of the resin filled in the first gate 240a and cured and a part of the resin filled in the second gate 240b and cured are the surfaces of the shroud 1 and the main plate 2. Remain. This is because, in order to completely remove each portion, precise polishing or the like is required, which causes an increase in manufacturing cost and is difficult to implement industrially. Such 1st gate trace part 1D and 2nd gate trace part 2D can be confirmed easily visually.

  When the resin includes a fibrous filler, the presence of the first gate trace portion 1D and the second gate trace portion 2D can be confirmed by observing the diffusion state of the fibrous filler using a microscope. .

  Specifically, the shroud 1 is first cut to prepare a sample including a cross section of the shroud 1 substantially parallel to the axial direction. Next, the cross section is observed using a microscope. When the resin contains a fibrous filler, in the resin molding method using a resin molding die, the filler in the resin is diffused so as to spread radially from each relatively narrow gate toward a relatively wide cavity. To go. For this reason, when the cross section is observed, if a converging point of the filler exists on the surface of the shroud 1 and a region in which the filler diffuses radially as the distance from the converging point is confirmed, the convergence is confirmed. The point can be regarded as the first gate trace portion 1D.

  Similarly, when a cross-section of the main plate 2 is observed with a microscope, when a focal point of the filler exists on the surface of the main plate 2 and a region in which the filler diffuses radially as the distance from the convergence point is confirmed, The convergence point can be regarded as the second gate trace portion 2D.

<Effect>
The effect of this embodiment is demonstrated.

  Resins generally tend to shrink when cured. For example, when the resin molding is integrally formed using a resin molding die, if the density of the resin filled in the cavity is non-uniform, the degree of resin shrinkage also becomes non-uniform. In particular, in a resin molded body having a shape whose area extends in the circumferential direction such as an impeller, if the resin contracts unevenly, distortion such as warpage tends to occur. The distortion of the shape in the impeller causes a reduction in the blowing performance.

  If an impeller having a configuration like the impeller 10 is produced using a resin molding die having only a gate that communicates with the shroud cavity, the distance between the gate and the main plate cavity is too long. The resin is not sufficiently filled, and as a result, the main plate is distorted.

  On the other hand, the resin molding die 200 of this embodiment includes a second gate 240b that communicates with the main plate cavity in addition to the first gate 240a that communicates with the shroud cavity. When the impeller 10 is integrally molded using the resin molding die 200, the first resin is injected into the shroud cavity via the first gate 240a and the shroud cavity is filled via the second gate 240b. In this case, the second resin is injected.

  For this reason, the phenomenon in which the resin filling in the main plate cavity is not uniform and / or insufficient as in the conventional case is suppressed, and as a result, the generation of distortion in the main plate 2 is suppressed. Will be manufactured. Therefore, the impeller 10 can exhibit stable air blowing performance.

  In the impeller 10 of the present embodiment, the first gate trace portion 1D is located on the first surface 1A of the shroud 1, and the second gate trace portion 2D is located on the third surface 2A of the main plate 2. As shown in FIG. 6, such an impeller 10 is manufactured by a resin molding die 200 having a simplified structure in which a first gate 240a and a second gate 240b are arranged on the first die side. be able to. Therefore, according to the impeller 10 of this embodiment, manufacturing cost can be reduced.

  In the impeller 10 of the present embodiment, the shroud has an opening 1C, and the main plate 2 is included in the opening 1C in a plan view as viewed from the axial direction of the impeller 10. As a result, the shape of the resin molding die 200 can be simplified, the manufacturing cost of the impeller 10 can be reduced, and the manufacturing yield can be improved.

  Moreover, the impeller 10 of this embodiment is located in the axial center side rather than 1st gate trace part 1D in 2nd gate trace part 1D in the planar view seen from the axial direction of the impeller 10. FIG. As a result, the shape of the resin molding die 200 can be simplified, the manufacturing cost of the impeller 10 can be reduced, and the manufacturing yield can be improved.

  Moreover, when the impeller 10 of this embodiment has a weld line, the weld line is preferably located on the main plate. FIG. 2 shows a case where the main plate 2 has a weld line 6. The weld line is a thin line that is generated when the resin flowing through the cavity of the resin molding die 200 is merged, and the surfaces of the merged resin are slightly solidified.

  The position where the weld line is generated tends to be lower in strength than other positions where the weld line is not generated. In the impeller 10, due to its shape, the strength of the blade 4 tends to be lower than the strength of the shroud 1 and the main plate 2. For this reason, when the weld line 6 is located in the blade | wing 4, there exists a concern that the blade | wing 4 may be damaged with the strength fall of the blade | wing 4 resulting from this.

  On the other hand, when the weld line 6 existing in the impeller 10 is located on the main plate 2, the strength of the main plate 2 is relatively high, and therefore there is little or no risk of damage due to the weld line 6. For this reason, the impeller 10 in which the weld line 6 is located on the main plate 2 can suppress the occurrence of breakage due to the weld line 6.

  Further, in the impeller 10 of the present embodiment, the first gate trace portion 1D is located immediately above the connection portion between the blade 4 and the shroud 1. Thereby, at the time of manufacture, the first resin can be sufficiently and uniformly filled into the blade cavity, and thus the uniformity of the shape of the blade 4 in the impeller 10 can be enhanced. The uniformity of the shape of the blades 4 leads to an improvement in the dynamic balance of the impeller 10. In particular, it is preferable that all of the first gate trace portion 1 </ b> D is located immediately above the connection portion between the blade 4 and the shroud 1. In this case, the above effect is further improved.

In the impeller 10 of the present embodiment, the dimension W ₁ of the first gate trace portion 1D is larger than the dimension W ₂ of the second gate trace portion 2D. In this case, at the time of manufacturing the impeller 10, it becomes easy to inject the first resin from the first gate 240a at a relatively high flow rate and inject the second resin from the second gate 240b at a relatively low flow rate. Thereby, the joining position of 1st resin and 2nd resin can be made into the cavity for main plates. Therefore, the possibility that a weld line exists in the blade 4 can be reduced.

  Moreover, in the impeller 10 of this embodiment, the number of 1st gate trace parts 1D is larger than the number of 2nd gate trace parts 2D. That is, in the resin molding die 200, the number of first gates 240a is larger than the number of second gates 240b. In this case, the flow rate of the first resin flowing into the shroud cavity from the first gate 240a can be made larger than the flow rate of the second resin flowing into the main plate cavity from the second gate 240b. Thereby, the joining position of 1st resin and 2nd resin can be made into the cavity for main plates. Therefore, the possibility that a weld line exists in the blade 4 can be reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 shroud, 1A first surface, 1B second surface, 1C opening, 1D first gate trace, 2 main plate, 2A third surface, 2B fourth surface, 2D second gate trace, 3 boss, 3a bearing hole, 4 blades, 5 outer ring, 6 weld line, 10 impeller, 20 fan, 40A, 40B primary heat exchanger, 50A, 50B secondary heat exchanger, 60A, 60B combustion device, 61 combustion tube, 62a-62d electromagnetic Valve, 63 gas proportional valve, 64 source gas solenoid valve, 65 gas pipe, 71-73, 75, 80-83, 85, 87 piping, 74 distribution valve, 76 pouring solenoid valve, 77, 78 check valve, 79 Atmospheric release valve, 84 Circulation pump, 86 Drain tank, 90 Bathtub, 91 Circulation adapter, 100 Water heater, BR1, BR2BR3, BR4 Combustion region, 200 Resin molding mold, 210 1st metal mold | die, 220 2nd metal mold | die, 230 cavity, 240a 1st gate, 240b 2nd gate.

Claims (11)

An impeller integrally formed of resin,
An annular shroud;
A main plate having a boss portion in the center portion;
A plurality of blades,
Each of the blades is disposed between the shroud and the main plate so as to connect the shroud and the main plate.
The shroud has a plurality of first gate traces,
The main plate is an impeller having a plurality of second gate traces. The shroud has a first surface and a second surface opposite to the first surface;
The main plate has a third surface facing the second surface, and a fourth surface opposite to the third surface,
2. The impeller according to claim 1, wherein each of the first gate trace portion and the second gate trace portion is located on the first surface and the third surface. The shroud has an opening;
The impeller according to claim 1 or 2, wherein the main plate is included in the opening in a plan view as viewed from the axial direction of the impeller.   4. The blade according to claim 1, wherein the second gate trace portion is located on an axial center side with respect to the first gate trace portion in a plan view as viewed from an axial direction of the impeller. 5. car.   The impeller according to any one of claims 1 to 4, wherein a weld line in the impeller is located on the main plate.   The impeller according to any one of claims 1 to 5, wherein the first gate trace is located directly above a connection portion between the blade and the shroud.   The impeller according to any one of claims 1 to 6, wherein a dimension of the first gate trace portion is larger than a dimension of the second gate trace portion.   The impeller according to any one of claims 1 to 7, wherein a number of the first gate trace portions is larger than a number of the second gate trace portions.   A water heater comprising the impeller according to any one of claims 1 to 8. A mold for resin molding for manufacturing the impeller according to any one of claims 1 to 8,
A cavity corresponding to the impeller,
A first gate provided at a position corresponding to the shroud in the cavity;
A resin molding die comprising: a second gate provided at a position corresponding to the main plate in the cavity. An impeller manufacturing method comprising:
Preparing a resin molding die according to claim 10;
And a step of injecting a resin into the cavity through the first gate and the second gate.

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